Star formation efficiency in turbulent clouds

Abstract

Here we present a simple, but nevertheless, instructive model for the star formation efficiency in turbulent molecular clouds. The model is based on the assumption of log-normal density distribution which reflects the turbulent nature of the interstellar medium (ISM). Together with the number count of cloud cores, which follows a Salpeter-like core mass function (CMF), and the minimum mass for the collapse of individual cloud cores, given by the local Jeans mass, we are able to derive the SFE for clouds as a function of their Jeans masses. We find a very generic power-law, SFE \propto (M_cloud/M_J)^{-0.26} and a maximum SFE_max \sim 1/3 for the Salpeter case. This result is independent of the turbulent Mach number but fairly sensitive to variations of the CMF.